Bryce's pad was PEF as far as I can tell. I had a CCF pad, which I had strapped to the back of my pack vertically after being rolled.
The CCF pad, from all indications, looked to have absorbed some water (from a test of squeezing it and seeing if any water extracted).
Now back in civilization and being able to do some more research(via a google search), the coated *surface* of CCF is moisture absorption resistant, but the material itself (ie the edges) is not.
This leads me to believe the following:
-If you were to dunk it in your sink it would absorb water.
-If you were to have it mounted vertically on your pack, the rain that hits the edge will absorb through the material
-If you were to have it mounted horizontally on your pack, the rain that hits the top and bottom surface won't absorb much, if at all, and can be wiped off, with minial absorption around the edges.